It has always been the goal of the food products industry to provide superior quality food products with a long shelf life. This allows the wholesaler and the retailer to purchase large quantities of food products when prices are low and store them until purchased by consumers. Thus, not only do the wholesalers and retailers benefit but ultimately the consumers do as well by being able to purchase food products at relatively low prices.
With the relative abundance of food and the increasing competition in the marketplace, the quality of the food products is becoming more and more important to promote sales. This is particularly true of vegetables and fruit. Consumers want fruit and vegetable products that maintain the overall appearance, including color and texture, as well as the flavor of fresh fruits and vegetables.
In order to meet this end, the food products industry relied for years almost exclusively on canning processes. Canned fruits and vegetables have a very long shelf life and largely maintain the desired appearance and fresh-like flavor. Canned products do, however, suffer from a number of disadvantages.
In particular, the canning process typically requires a relatively large level of salt in order to maintain the flavor of the fruits and vegetables. Recent growing awareness of the physical complications, including hardening of the arteries, caused by excessive levels of salt in the body has led the consuming public to look toward food products packaged with lower levels of salt. As such, canned products are growing in disfavor.
Another problem with canned products relates to their overall weight. More specifically, in order to maintain as much of the original flavor of the food products as possible, the canned products are often packaged in a large amount of water. Both the water and the cans themselves often weigh as much or more than the actual food product itself. Thus, the water and the cans significantly add to the cost of transporting food products from one location to another. The weight also makes the cans relatively cumbersome to handle. Many consumers dislike canned fruits and vegetables for this reason. As such, alternative methods for processing and packaging fruits and vegetables are quickly embraced by many consumers.
In response to this demand for an alternative to canned fruits and vegetables, dehydrated products have made a relatively large inroad in the marketplace in recent years. Dehydrated products are gaining in popularity with producers because they are relatively simple to package. Dehydrated products may be packaged in sealed foil or plastic pouches. As such, the overall cost of the packaging is reduced. In addition, it should be recognized that plastic and foil packaging is less bulky than cans and, as such, inventory controls and storage space requirements are simplified and reduced.
From the consumer's point of view, the pouches are relatively easy to handle and store. The food products themselves are also easily utilized by simply rehydrating in water and then serving. In addition to this added convenience, many consumers find that the dehydrated products have a good flavor resembling that of fresh produce.
There are two primary approaches presently being followed to produce dehydrated food products. These are by freeze drying and air drying.
In freeze drying, a frozen food product is placed in a vacuum vessel, brought to a processing vacuum and then heated. Because of the vacuum, the water in the product sublimates, that is, changes phase directly from a frozen or solid state to a gaseous state.
Freeze dried products are of excellent overall quality. The products are not exposed to high temperatures during processing which might degrade quality. The internal cell structure of the products is also retained. As such, freeze dried products have an appearance and flavor more closely conforming to their fresh food counterparts. They also, advantageously, have a fast rehydration rate and, therefore, may be more quickly prepared by consumers. Food processors, therefore, find them to be superior quality ingredients for the formulation of convenience consumer products.
A significant drawback to freeze dried food products is, however, the processing costs. More specifically, freeze drying is an energy and capital intensive and slow process. Further, food products formulated with freeze-dried ingredients also become relatively expensive. For many foods, this additional cost drives the price of products formulated with the freeze dried food ingredients to a level unacceptable to consumers. As such, despite the improved appearance and added flavor, freeze dried dehydrated products have not always been successfully received in the marketplace.
In air drying, the food products may be dried at ambient temperature, but more typically are placed in dryers such as fluidized bed, continuous belt, or tray dryers in order to remove moisture with heated air. While the air drying procedure is relatively inexpensive when compared to freeze drying, it does suffer from a number of shortcomings. In particular, the resulting food products and particularly fruits and vegetables exhibit relatively low quality. For example, certain air dried products such as apples undergo a change in appearance during air drying, losing their color and to a certain extent, their texture. In some situations the flavor may also be affected. These factors make air dried food products less appeasing to consumers who prefer an appearance and taste as closely as possible corresponding to that of the fresh produce.
Another problem with air dried products has to do with their rehydration rate. Air dried products take a relatively long period of time to rehydrate, that is for the dehydrated product to resaturate with water. Since it is often the desire of the food processor to provide a food product of the convenience variety which may be quickly prepared and served, this characteristic can be a significant drawback.
In order to address these problems with air dried products, a steam puffing process has been developed. After the product is initially air dried to 15 to 35 percent moisture wet basis, it is pressurized in a steam gun with super heated steam. Next, the product is puffed by quick release from the steam gun. It is then subsequently air dried to the desired moisture content.
This process does serve to increase the volume and internal porosity of the dehydrated product. As such, rehydration rates are advantageously increased. A problem arises, however, as the high temperature to which the product is subjected during its time in the steam gun can change product characteristics such as texture, nutrients, color and flavor. This, of course, reduces the appeal of the resulting product to the consuming public. Thus, a need is clearly identified for a new puffing process.